There is a need in the art for improved photochromic articles such as coatings, films, and optical elements. Most successful commercial applications of photochromic articles are related to ophthalmic lenses that darken in the sun and return to their initial transparency in typical indoor light. Some niche markets include the security ink and the entertainment/toy markets. There are technical challenges that prevent this technology from entering the vehicles, windows, and structural glass markets, including durability, fatigue, and switching time. The organic dyes that have been used in a majority of the photochromic systems are degraded by light and oxygen and thus their lifetimes suffer. Typical known materials do not compare well with the traits desired, for instance, in a photochromic system designed for window applications.